The driving of reinforced concrete and H-beam piles is of fundamental importance in an array of construction and building applications. Various pile-driving techniques exist involving the use of a range of pile-driving devices.
One form of existing pile-driving devices is the hammer piling device. Hammer piling devices include a hammer, which is used to repeatedly free-fall on the upper end of a pile to drive it into the ground. The hammer is mounted in an upstanding steel frame and is lifted within the frame using a hydraulic lifting assembly. The steel frame may be mounted directly on the ground at a location in which it is desired to hammer a pile. Alternatively, the steel frame may be mounted on the tray of a truck in order to provide mobility to the device. Advantageously, hammer piling devices are relatively cost effective to manufacture and use and, if mobile, relatively easily movable between piling sites. One major disadvantage of hammer piling devices is that repeated impact of the hammer on the upper end of the pile is very noisy. Indeed, the repeated hammer impact on the pile can generate ground vibration that is not only unpleasant, but can lead to structural damage of surrounding buildings and other structures.
Another option exists in the form of hole boring devices. Rather than hammering a pile into the ground, a hole can be bored into the ground to the required depth, following which a pile is placed into the hole. Hole-boring devices incorporate a downwardly directed rotating bore rotatably mounted within a steel support frame. The bore is rotated by a suitably configured rotating mechanism. The frame may be mounted directly on the ground at a location in which it is desired to bore a hole. Alternatively, the frame, rotating bore and rotating mechanism may be mounted on a truck tray in order to provide a mobile arrangement.
Boring devices provide the benefit of generating less noise and unpleasant and potentially damaging vibrations in the area surrounding the boring site. Boring devices are also effective for use in large-scale piling operations. Disadvantages of using boring devices include the fact that they have generally higher operating costs when compared to hammer piling devices. It is also more time consuming to bore a hole than hammer a pile. A dedicated area must also be temporarily provided in the vicinity for placing soil to be used in backfilling a pile hole. This can be inconvenient on cramped sites.
It is possible to use a boring device in conjunction with a hammer piling device. In this regard, a hole may be initially partially pre-bored using a boring device. A pile may then be inserted into the partially pre-bored hole and a hammer piling device then used to hammer the pile to the desired depth. Partially pre-boring the hole advantageously reduces the amount of vibration generated when compared to using a hammer piling device for the entire process. However, drawbacks do exist in partially pre-boring a hole, including increases in time and cost. Further, partial pre-boring is generally only useful in applications of limited capacity.
Hence, each of the above-described techniques has associated shortcomings.
Hydraulic piling devices (often referred to as “silent piling devices”) have been developed in an attempt to address at least some of these shortcomings. The general configuration of hydraulic piling devices is to include an upstanding support frame, with one or more hydraulic jacking cylinders connected to and extending downwardly within the frame. An arrangement for engaging an upper end of a pile is generally connected to a lower end of the jacking cylinders. Alternatively, the arrangement for engaging an upper end of a pile is replaced with a gripping arrangement for gripping around the pile. The gripping arrangement would typically also be connected to a lower end of the jacking cylinders.
In such an arrangement, extension of the hydraulic cylinders causes the pile to be forced (or pushed) into the ground. Counterweights are typically provided on the support frame to ensure that extension of the hydraulic cylinders forces the pile into the ground, rather than causing the hydraulic piling device to lift upwardly from the ground.
One advantage of hydraulic piling devices is that they generate far less noise and ground vibration when compared to hammer piling devices.
Disadvantages of many existing hydraulic piling devices include the relatively time-consuming process of moving those devices from one piling site to another piling site. This is exacerbated by the design of these devices, which require counterweights to be unloaded from the device before the device can be moved. The counterweights then have to be reloaded onto the device before it can be used to drive a pile at the next site.
The time-consuming process of moving many existing hydraulic piling devices is also undesirable in instances where a large object such as a rock is encountered during the piling process. A partially driven pile can undesirably create an extended downtime, as it is usually necessary to first break off the portion of the pile extending from the ground before going through the process of moving the piling device to another location.
The support frames of many existing hydraulic devices have a height approximating twice the pile length. This height can result in an inherently unstable device, which must be taken into consideration when moving, installing and operating the device.
A still further problem of many existing hydraulic piling devices is the fact that they are not adequately designed for operating on sloping or uneven ground.
Yet another problem with existing hydraulic piling devices is that it is not generally possible to drive a pile adjacent an existing object, such as wall, building or other structure, given that the support frames of existing devices are configured to surround the pile being driven into the ground. Thus, a space sufficient to temporarily accommodate the frame must be provided between the existing object and position of the pile-driving site.
The inventor has addressed a number of the aforementioned problems of many existing piling devices by designing a hydraulic piling device, the subject of International Patent Application No. PCT/SG2003/000177 (WO 2004/042152), the entire contents and disclosure of which is incorporated herein by reference. That device addresses the inherent instability of earlier hydraulic piling devices by providing a wider and more stable footing for support of the frame, hydraulic jacking cylinders and gripping arrangement when compared to that of existing hydraulic piling devices. The device also provides maneuverability of the frame, hydraulic jacking cylinders and gripping arrangement by providing frame-mounted footings that are movable relative to respective ground-mounted footings. This arrangement also provides for the movement of the device irrespective of whether counterweights are mounted thereon, thereby avoiding the need to unload the counterweights before moving the device.
Further, the device allows for the removal thereof from around a pile partially extending from the ground. This is possible because of the provision of openings provided in the opposing sides of the frame. The device can also be effectively used on sloping or uneven ground by the vertical adjustment of the frame-mounted footings relative to the respective ground-mounted footings.
The inventor's hydraulic piling device, the subject of International Patent Application No. PCT/SG2003/000177, has, therefore, provided considerable advances in piling devices generally and hydraulic piling devices in particular.
Nevertheless, it would be desirable to further improve the stability of existing hydraulic piling devices.
It would also be desirable to further improve the maneuverability of existing hydraulic piling devices.
It would be still further desirable to provide an arrangement enabling the driving of a pile adjacent or at least close to an existing object or structure.